Alternating-current-rectifying apparatus.



0. P. STEINMETZ. ALTBRNATING CURRENT REOTIFYING APPARATUS.

APPLIOATION FILED MAR. 23, 1903.

1,095,170, Patented Apr.28, 1914.

Witnesses |n-/ent,orl Charles PSbeinmebz aw/W +4 is ffbb orneg 11 and 12 of oppositepolarity, extend from whereby current either of high or low volt- .in the diiii'erent phases of the system, the

UNITED STATES PATENT oF IoE,

CHARLES P. S TEINMETZ, SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ALTERNATING-CURRENT-RECTIFYING APPARATUS.

Specification of Application filed March 23,

To all 1.0710712 it may concern Be it known that I, CiiARLns I. 'STEIN- nn'rz, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Alternating-Current-Rectifying Apparatus, of which the following is a specification.

My invention relates to the rectification. of alternating current and comprises means age may be rectified without the use of any apparatus with moving parts.

My invention contemplates more especially the rectification of multiphase alterhating currents though it is to be understood that certain-of its features of novelty are applicable also to single phase alternating current systems. When the rectification of multiphase alternating current is undertaken, I derive from each phase of the system a series of current impulses of a single polarity, the impulses. or half waves being of the same polarity "for allof the phases. These half waves -I combine to produce a substantially uniform resulting currentQ Due to the phase displacement of the waves maxima and minima of the half waves ocour in overlapping sequence, so that the sum of the instantaneous values of all the half waves taken together is practically constant.

For a more detailed understanding of my invention reference is to be had to the following specification taken in connection with the accompanying drawings in which Figure-1 represents diagrammatically one embodiment of my invention; Fig. 2 a modified form, while Fig. 3 shows arrangements possessing various valuable improvements.

The novel features which characterize my invention I have pointed out with particularity in the appended. claims.

In Fig. 1 I have represented a system for rectifying three phases of current. In this case the threephase current is supplied through a set of three-phase transformers having primary windings 1, 2 and 3 and corresponding secondaries 4, 5 and 6. Two sets of three-phase leads 7,, 8 and 9, and 10,

opposite ends, respectively, of the three secondaries, the middle points of wln ch are connected together to form a point of neutral potential. To each set ofleads I connect a Letters Patent Patented Apr. 28, 1914.

1903. Serial No. 149.112;

rectifying device, consolidated, so to speak, so as to form a single structure. One of these rectifying devices is indicated at 13 and. the other at 14 and both being of the same construction a description of one is suflicient for both.

The device 13, for example, comprlses a very highly exhausted receptacle or envelop, and communicating with the interior of this envelop are four main electrodes 15, 16, 17 and 18, and a supplementary or auxiliary electrode 19. All of these electrodes may be of mercury or of some other suitable vaporizable material, though in the present instance .I find it convenient to make some of the electrodes, as for example the upper electrodes 15, 16 and 17 of some solid mater1al,"such as iron, artificial graphite, steel, or the like. The mercury electrodes 18 and 19 are separated slightly from each other and the space between them forms the seat of an electric are produced by a small storage battery 20 or other suitable source of direct current connected to theexterior terminals of the electrodes, this are being initiated when the electrodes are brought into temporary electrical engagement with each other byshaping the tubeso'as to cause'the mercury forming a portion of one or the other of the electrodes to run over the slight barrier 21 normally separating the bodies of mercury constituting the electrodes. (I A spark or are once established by the means mentioned, or by any other means such as may be known to one skilled in the art, may be continued indefinitely and, by giving off ions orelectricallyconducting vapor, operates in such a manner as to cause a flow of current between the main electrodes of the device, due to the impressed alternating voltage. This flow of current, however, is not alternating but consists of a series of pulsations of one polarity, the effect being one in which all of the waves of the alternating current of a single polarity are completely suppressed, and the other waves allowed to pass. The'other rectifying device 14: is similarly provided with a supplemental as a companion to the rectifying device 13 recei es current from the set of mains 10,

v to supply the direct current produced by system. This point of neutral potential is nected transformers, such for example as the .transformer incapable of delivering, in the small proportion, say 7 to 10 per cent, of its .stantly produced and the transformer core 11 and 12. It is started in the same manner as the rectifier 13, by means of an auxiliary are maintained between the mercury cathode 22 and an auxiliary anode or electrode 23. This auxiliary arc receives its energy from a source of direct current such as a storage and 22 of the respective rectifying devices 13 and 14: are electrically connectedas indicated, and a common return or neutral conductor 25 extends from a point of neutral potential of the alternating 'current providedin the present instance by connectthe neutral conductor to a central point in each of the secondary windings 4, 5 and 6 as indicated. I g

' In the circuit, with the neutral or return conductor '25 I connect any direct current translating devices to which I may desire the rectifier. In the present instance I have represented a storage battery 26, as an example of such translating device; though it is to be understood that m place thereof or in conjunction therewith I -may utilize any other suitable translating device, such for example, as direct current motors 27, are orincandescent lamps 2 or the like. I

When the arrangement shown in Fig. 1

is started into operation by means of the auxiliary arcs fed from the storage bat. teries 20 and 24, a series of waves or pulsations of current of one polarity flow through the rectifiers to the consumption circuit represented by the lamps, motors, and storage batteries and back through the neutral conductor 25 130 the middle points of the so? ondary windings 4, 5-and 6. It will be evident-therefore that a half wave of current will flow first 'one half of each winding and then in the other half: The half waves which flow in one half the winding will magnetize in the opposite direction from the waves in the other half-of the winding. A resultant alternating magnetization is con therefore does not become saturated as would be the case if the reSuItihg magnetiZation' were unidirectional. This lattereliect would take place for example if the unidirectional current were fed into the neutral of Y-conusual Y-connections for three-phase transformers; and it is objectionable becauseit involves so large a flow of magnetizing current to the transformer as to render the form of direct current, more than a very rated: output.

By reason of the connection above de scribed, the secondaries 4, 5 and 6, though deriving energy from the three-phase source,

supply six phase current. .Waves of one polarity pass, for example, to the rectifier 13 and when these polarities reverse, waves pass to the other rectifier 14. The rectifiers. 13 and 14 therefore to a certain extent constitute selective circuits. As a result of the action mentioned, thesecondaries produce alternating reactions upon their corresponding primaries which, therefore, requireno more than the usual amount of magnetiz mg current If a secondary were to carry current during one-half wave and not durmg the other a unidirectional magnetization of the core ofthe transformertwould occur and this would require an excessive magnetizing current to produce the requisite counter electro-mot-ive force in the primary. By the arrangement described, this serious disadvantage which in practice may amount to practical inoperativeness, is avoided, while at the same time current waves are .derived which are combined in the return circuit including the translating device so and a consequent higher degree of uniformity and steadiness of current.

When the auxiliary sources of current, 20- and 24 are maintained in operation continuously to produce the auxiliary arcs in the rectifiers l3 and 114, it will be apparent that the translating devices in the consumption-circuit may be entirely removed from circuit-and that, when again cut in, the rectifiers will start automatically. If, however, the starting means are .not maintained in continuous operation, and it is not ordinar ily necessary that they should be, I may connect a resistance 29permancntly in the consumption circuit, thus preventing the current from falling below a certain minimum value. The rectifieis are apt to cease 4 operations if the current in the consumption circuit gets too low,and the value of thereslstance in the consumption circuit is therefore chosen so thatZe-ven if all the translating devices are out of circuit, the current will not fall below its minimum value.

rings and leads to a set of three-phase transformers 32 which in turn are connected through leads 33 across the supply mains. for the main transformer primaries 1, 2 and 3. The inverted rotary and the transformers 32 are adjusted relatively to each other so that the voltage impressed upon the direct current end of the inverted rotary tends to produce upon the mains 33 a voltage which is higher than that of the main supply conductors 34. By reason of this adjustment energy is received in the form of direct current and returned to the main cir cuit as alternating current, thus preventing the waste of energy which would otherwise occur in heating the resistance replaced-by the inverted rotary.

Though I have shown the energy returning device in connection with Figs. 1 and 2, it is tobe understood that it may be employed in connection with the system illus? trated by Fig. 3. To avoid useless repetition, however, I have not illustrated it in Fig. 3.

In the system shown in Fig. 3 an arrangement is provided for utilizing both waves of current derived from a Y-connected system of transformers, the secondaries of which are-indicated at 62, 63 and 64. A rectifier 65 of the same constructiofi as that heretofore described, receives current from the Y- connected secondaries which, after Passing through translating devices such as 66 and 67' returns through counter-magnetizing coils 68, 69 and 70 to the neutral of common connection of the Y-connected secondaries. From the leads extending to the rectifier 65 are branched a corresponding number of conductors 71, 72 and 73, which extend respectively to three rectifying devices 7 L, 75 and 76 all alike. Each of these devices comprises a hi 'hly exhausted receptacleof tubular form, tiough it may be understood that the form of the envelop may be widely va-' ried without departing from my invention, and each is provided with two anain electrodes and a supplemental or auxiliary electrode. As in the case of the other rectifiers herein described, all of the e electrodes may be of mercury or of other suitable vaporable material, though in the present instance I find it convenient to make one of the electrodes, as for example, the upper electrode, of some solid material such as iron or artificial graphite. The starting means is essentially the same as that herein described in connection with the rectifiers of Fig. 1. Connections are made to these rectifiers T1, 75 and 7 6 so that current waves will pass through them of a polarity opposite from that of the waves passing to the rectifier 65. For that purpose leads 71, 72, and 73 are connected to the mercury electrodes of the rectifiers 74, 75 and 7 6 as distinguished from the connections of the same supply circuits to ,the carbon or non-vaporizable electrodes 77 of the rectifier 65. Waves of one polarity, therefore, ass into the rectifier 65 and rectifiers, whereby the secondaries 62, 63 and 64 of the supply transformers are at all times loaded with alternating current. The upper or non vapcrizable electrodes 78, 79 and 80 of the threc single-phase rectifiers are joined together and the waves of current passing through are therefore combined, to form a nearly steady direct current in the return conductor 81 by which current is conveyed to' another set of translating devices, such as a storage battery 82 or lights 83. The two sets of translating devices are connected, as indicated sothat athree-wire system is formed, the neutral conductor of which is indicated at 8st and is connected as before intimated, to the circuit of the common magnetizing coils 68, 69- and '70 leading to the, neutral of the Yconnected secondaries. It, will be evident that when the loads on the two sets of the three-wire systems are equal, no current will flow over the neutral conductor 8 t. lVhen,'however, the loads become unequal, current willfr'eturn to theneutral of the Y-connected secondaries and, when returning, its magnetizing effect in. passing through the counter-magnetizing coils will counterbalance a undirectional magnetization in the secondaries 62, 63 and 64 due to the inequality of the waves of one polarity ,with respect to the waves of opposite p'o-' larity. Resistance 85 and 86 may be connecteds across the three-wire system to fulfil in connection with rectifier 65, the functions fulfilled by resistance 29 of Fig.1 with respect to its rectifiers 13 and 14.

Although in the foregoing description and in the figures of the drawings I have set forth certain specific embodiments of 1ny invention, it is to be understood that various modifications thereof may be made without departing from my invention, for which reason I do not wish to be limited to the details show \Vl iat I claim as new and desire to secure by Letters Patent of the United States, is,

1. The combination of a multiphasealten ,nating currentsystem, a set of conductors connected respectively to a terminal of each phase of said system, a vapor rectifying device having anodes connected to said conductors, a second set of conductors connected respectively to a terminal of opposite polarity of each phase, a second vapor rectifying device having anodes connected to said second set of conductors and a direct current load circuit connected to the cathode circuit of each of said rectifying devices and to points of intermediate potential on the phases of said system.

natin current, "a vapor rectifier therefor contalning arc paths of constant length, a

waves of opposite polarity through the other 2. The combination of a source of alter direct current circuit, means forming a permanent part of saidcircuit for insuring a flow of current from said source in said rectifierof a value above that at which the operation of the rectifier becomes unstable and translating devices in said circuit for utilizing the remaining part of the rectified current.

3. The combination of a source of alternating current, a vapor rectifier therefor, means for-insuring a flow of current in said rectifier of a value above that at Which the operation of the rectifier becomes unstable, and means for returning energy from the rectifier circuit to said source.

4. The combination of a source of alternating current supply, a mercury vapor rec tifier fed therefrom having are paths of pre determined length, an invariable currentrcceiving circuit for maintaining the amount of rectified current above a value at which the rectifier becomes unstable and translateing devices for utilizing at Will the remaining capacity of the rectifier.

5. The combination of a source of alternating current, a vapor rectifying device, a circuit supplied continuously by the rectifier With a predetermined amount of current, and means for returning energy from said circuit to the supply system.

6, The combination of an alternating cur rent supply system, a vapor rectifier, an energy-consuming device and an energy-transforming device in circuit With said rectifier, and means for returning to the supply system energy received by the transforming device.

7. The combination of a source of alter-. nating current, a consumption circuit con- "taining removable translating devices, a

mercury vapor rectifierhaving arc paths of constant length between said source and said nating current, a consumption circuit eontaining devices taking a variable amount of current, a rectifier receiving energy from said source and supplying current to said consumption circuit, said rectifier being liable to cease operating when the energy transmitted from said source falls below a predetermined limit, and means forming a permanent part of said consumption circuit for insuring the continuous flow through sa1d rectifier of sufficient current from said source to insure stability of the rectifier.

9. The combination of a source of poly phase current, a consumption circuit, containing translating devices removably connected therein, a rectifier which is self maintaining when the current in said consumption circuit is normal but unstable when said current is low, and a permanently connected current receiving means for continuously maintaining enough current from said source through said rectifier to keep the rectifier in stable operating condition.

In witness whereof, I have hereunto set my hand this 20th day of March, 1903.

CHARLES P. STEINMETZ. itnesses EDWARD WILLIAMS, Jr., HELEN ORFORD. 

